In recent years, fluid machines represented by a scroll compressor and the like, include a rotation preventing pin projected from a wall surface at the side of a housing or at the side of a turning scroll, and a restraining member that restricts the position of the rotation preventing pin by engaging with the rotation preventing pin, as a rotation preventing mechanism of the turning scroll with respect to the housing.
As conventional fluid machines employing such a structure, a technology disclosed in Patent Document 1 is known. In the conventional fluid machine (scroll compressor), a fixed scroll that has a substrate and a scroll portion, and a movable scroll that has a substrate and a scroll portion, are arranged in a housing in a state that the scrolls are meshed with each other in the scroll portions. Accordingly, a compression chamber is formed between both scroll members, and gas is compressed by moving the compression chamber towards the center of the scroll portions from the outer peripheral side thereof, by revolving the movable scroll around the shaft center of the fixed scroll. As a mechanism that prevents the movable scroll from rotating and allows its revolution, a plurality of pairs of fitting holes is formed in the substrate of the movable scroll and in the inner wall of the housing facing thereto, the rotation preventing pin is pressed into each of the fitting holes, and a rotation preventing ring (restraining member) is inserted and fitted between projecting ends of each of the pair of the rotation preventing pins. In such a scroll compressor, a chamfered portion smoothly connected with the outer periphery of the pin is formed at the outer peripheral rim of the end at the side of the fitting hole of each of the rotation preventing pins.
[Patent document 1] Japanese Patent Application Laid-open No. H8-338376